ROD AS 3786611 - Caterpillar

circuits between the Brake ECM and the Motor 2 ECM are not open. Before proceeding to the next step, disconnect the jumper wire that is connected to the Motor 2 ECM J1 connector contacts. Proceed to Test Step 3.
NOT OK - The resistance measurement is greater than 5 ohms. There is an open circuit or a bad connection in the CAN A Data Link circuits between the Drivetrain ECM and the Motor 2 ECM.Repair: To isolate the location of the open circuit, disconnect the machine harness connector CX-C4 from the cabinet connector CN2. There are two sets of CAN A connections on these connectors. With the jumper wire still connected at the Motor ECM J1 connector, a resistance measurement between the cabinet side CN2 contact 38 or contact 23 (wire CANAH / wire 956-YL(Yellow)) and contact 39 or contact 24 (wire CANAL / wire 957-GN(Green)) should measure 5.0 ohms or less. If the resistance measurements are higher, study the connection diagram at the beginning of this procedure to isolate the area where there could be a problem.The same type of resistance measurement can be taken at the CX-C4 harness connector to determine is the problem is in the circuits that are outside of the Inverter cabinet. The illustration at the beginning of this procedure shows the correct connection order for the controls that are outside of the cabinet. The diagram does not show all the harness splices outside of the cabinet. For system connections outside of the Inverter Cabinet, refer to the complete machine electrical schematic that is in the Service Manual.The circuits that are connected in series for some of the controls will have to be checked individually. A resistance will not measure through the control circuits when the power is off.Locate and examine all the circuit connections that are used in the suspected sections of the data link circuit. Check each wire section from connector to connector for an open or a bad connection. Ensure that all connections are clean, secure, and in good condition.Find the open circuit or poor connection in the data link circuits to resolve this problem.STOPTest Step 3. CHECK THE DATA LINK CIRCUIT FOR A SHORTNote: A short circuit in the system would most likely cause all the control modules in the system to activate this diagnostic code. However, since no open circuits or poor connections have been found, a short circuit could be causing the problem.The key switch and the battery disconnect switch remain in the OFF position. The cover for the low voltage ECM compartment is removed.The Motor 2 ECM J1 connector remains disconnected.The jumper wire that was used in the last step is disconnected.
At the Motor 2 ECM, disconnect the J2 harness connector.
At the Motor 2 ECM, measure the resistance between the CAN A positive circuit at contact J1-53 (wire CANAH) and a good cabinet ground point. Measure the resistance between the CAN A positive circuit contact J1-53 and all the other circuits (except CAN A negative circuit contact